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CVE-2026-34401

6.5 · MEDIUM

XML Notepad is a Windows program that provides a simple intuitive User Interface for browsing and editing XML documents.

Published Mar 31, 2026CWE-611EPSS 1.39%

Overview

CVE-2026-34401 is a medium-severity vulnerability. It was published on March 31, 2026 and has a CVSS 3.1 base score of 6.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.5, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

XML Notepad is a Windows program that provides a simple intuitive User Interface for browsing and editing XML documents. Prior to version 2.9.0.21, XML Notepad does not disable DTD processing by default which means external entities are resolved automatically. There is a well known attack related to malicious DTD files where an attacker to craft a malicious XML file that loads a DTD that causes XML Notepad to make outbound HTTP/SMB requests, potentially leaking local file contents or capturing the victim's NTLM credentials. This issue has been patched in version 2.9.0.21.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/microsoft/XmlNotepad/commit/3665603d61ba10b7827a3724e854748cb780140cGitHubgithub.com/microsoft/XmlNotepad/commit/c03ab2311ac6960452eb1ab49098768f851dcc53GitHubgithub.com/microsoft/XmlNotepad/releases/tag/2.9.0.21GitHubgithub.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42chGitHubgithub.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch

How CyberStrike helps

Frequently asked questions

What is CVE-2026-34401?

CVE-2026-34401 is a medium-severity vulnerability. It was published on March 31, 2026 and has a CVSS 3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-34401?

This vulnerability has a CVSS 3.1 base score of 6.5, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-34401?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-34401?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-34401 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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